亚热带河口潮滩湿地N2O排放对氮硫增强输入的响应

以亚热带区域闽江河口短叶茳芏中、高潮滩湿地为研究对象,于2014年7月至11月进行氮硫增强输入的实验,利用静态箱-气相色谱法测定潮滩湿地中N_2O排放通量,并同步测量相关的环境因子.结果显示,不同潮滩湿地N_2O排放通量对氮硫增强输入的响应存在差异,但总体上看均促进了N_2O的排放.与对照相比,NH_4~+-N输入使中、高潮滩排放通量分别提高了157.97%和236.36%;NO_3~--N输入使中潮滩提高了60.95%,而使高潮滩N_2O排放通量提高了246.77%;SO_4~(2-)-S输入分别使中、高潮滩N_2O通量提高50.68%和87.17%;而N-S复合输入则使中、高潮滩N_2O通量分别增加了84.20%和117.79%.不同的处理组对中、高潮滩的N_2O排放通量的促进作用分别表现为:NH_4~+-NN-SNO_3~--NSO_4~(2-)-S及NO_3~--NNH_4~+-NN-SSO_4~(2-)-S.氮硫增强输入改变了短叶茳芏潮滩湿地N_2O排放通量的变化规律,但除了NH_4~+-N处理对高潮滩N_2O排放通量的影响显著外,其他处理组的影响均未达到显著性水平.中、高潮滩湿地N_2O的排放通量与沉积物温度、含水率具有显著的相关关系,而与电导率相关性不显著.随着全球环境问题的日益严重,系统研究湿地生态系统N_2O排放的机制与规律,对于科学准确的估算全球温室气体排放量具有重要的意义.

Effect of enrichment of nitrogen and sulfate load on N2O fluxes from tidal flat wetland in the subtropical estuary

Using enclosed static opaque chamber methods, the effects of nitrogen and sulfate enrichments on sediment to atmosphere nitrous oxide (N₂O) fluxes were studied from July to November in 2014 at the middle-and high-tidal zones of a subtropical Cyperus malaccensis wetland in the Min River estuary. The environmental factors controlling N₂O flux were also measured. The results showed different responses of gas flux to the nitrogen and sulfate enrichments at different tidal zones and generally the fluxes were enhanced by the exogenous nitrogen and sulfate loadings. Compared with the N₂O flux in control treatment without nitrogen or sulfate loading, the fluxes under the ammonium addition at the middle and high tidal zones was increased by 157.98% and 216.04%, respectively, and the fluxes under the nitrate addition were increased by 60.95% and 246.77%, respectively at these two tidal zones. Under sulfate addition the N₂O fluxes at the middle and high tidal zones were 1.51 and 1.87 times, respectively as that of the control treatment, and the fluxes under both nitrogen and sulfate input were increased by 84.20% and 117.79%, respectively at the two tidal zones. The effects of different treatments on the N₂O flux at the middle intertidal zone decreased in following order:NH₄⁺-N > N-S > NO₃^--N > SO₄²-S, and in order of NO₃^--N > NH₄⁺-N > N-S > SO₄^2--S at the high intertidal zone. The enrichments of nitrogen and sulfate changed the variation of N₂O fluxes in the growing season of C. malaccensis; however, significant effect was only observed at the high intertidal zone under ammonium addition. The sediment temperature and moisture were found to significantly correlated to the N₂O fluxes while there was no significant correlation between the sediment conductivity and N₂O fluxes at the two tidal zones. In the context of increasingly serious global environmental problems, systematical studies on the mechanisms and patterns of the N₂O emissions from wetlands are highly important for the accurate estimation of global greenhouse gas emission.